A play car of mass m 1 = 0.18 kg and velocity of magnitude 3.90 m/s collides wit

ID: 1399509 • Letter: A

Question

A play car of mass m1 = 0.18 kg and velocity of magnitude 3.90 m/s collides with a 1.20 kg play car moving in the opposite direction at 1.00 m/s

What is in Kg m/s the overall momentum of the pucks before the collision?

b)What is in Joules the overall kinetic energy of the pucks before the collision?

After the collision, m1 bounces back with a speed of 2.31 m/s.

c)What is in m/s the speed of the second puck after the collision?

d)What is in Joules the overall kinetic energy of the pucks after the collision?

a) overall momentum of the pucks before the collision,

Pi = m1*u1 + m2*u2

= 0.18*3.9 + 1.2*(-1)

= -0.498 kg.m/s

b) the overall kinetic energy of the pucks before the collision,

Ki = 0.5*m1*u1^2 + 0.5*m2*u2^2

= 0.5*0.18*3.9^2 + 0.5*1.2*1^2

= 1.97 J

c) Apply conservation of momentum

Pi = Pf

Pi = m1*v1 + m2*v2

-0.498 = 0.18*(-2.31) + 1.2*v2

==> v2 = (-0.498 + 0.18*2.31)/1.2

= -0.0685 m/s

speed, |v2| = 0.0685 m/s

d) Kf = 0.5*m1*v1^2 + 0.5*m2*v2^2

= 0.5*0.18*2.31^2 + 0.5*1.2*0.0685^2

= 0.483 J

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